Avalanche Canada pmarshall, Avalanche Canada

Sea to Sky Avalanche Forecast

Dec 14th, 2012 8:56AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Storm Slabs and Wind Slabs.

Avalanche danger should rise rapidly throughout the day on Saturday as snow accumulates and winds pick up.



Fair - Intensity of incoming weather is uncertain

Weather Forecast

Synopsis: A series of frontal systems bringing moderate to heavy snowfall and strong winds will affect the South Coast for the next few days.Saturday: Moderate snow – 15-25 cm. Winds increase to strong from the SW. The freezing level should remain around 500-600 m. Sunday: A short break early in the day, then moderate to heavy snow overnight and into Monday (~15 cm). Winds increasing to strong from the SW with the arrival of the system. Freezing level around 600 m. Monday: Heavy snow. Freezing level could jump to 800 m.

Avalanche Summary

Recent reports include numerous natural and human triggered loose snow avalanches and a few small human triggered slab avalanches in exposed wind loaded features near ridge top. Clear weather on Wednesday revealed a few older natural avalanches up to Size 3 on northerly aspects in the alpine. These events may have released on the late November surface hoar layer.

Snowpack Summary

Up to 30 cm of new snow on Thursday may have buried a thin layer of surface hoar in some areas. Recent winds have been stiffening the low density storm snow and forming reactive slabs in exposed lee terrain. Below the recent storm snow weaknesses, the snowpack is well settled and strong. A layer of surface hoar that formed during late November has been found intact or decomposing in some locations down a meter or more. The early November crust/facet combination near the base of the snowpack seems to be dormant, at least in deep snowpack areas where it is buried too deeply by a stiff snowpack to be affected by light triggers on the snow surface.


Storm Slabs

An icon showing Storm Slabs


Very Likely - Likely

Expected Size

1 - 4
Weaknesses are likely within or below the new storm snow and may be triggered naturally or by the weight of a person or snowmobile.
Stick to non-avalanche terrain or small features with limited consequence.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>


All aspects.


All elevations.

Wind Slabs

An icon showing Wind Slabs


Very Likely

Expected Size

1 - 4
Expect to encounter touchy wind slabs below ridge crests, behind terrain features, and in cross-loaded gullies.
Avoid lee and cross-loaded terrain near ridge crests.>


North, North East, East, South East.


Alpine, Treeline.

Valid until: Dec 15th, 2012 2:00PM